What muscle group would you say is the biggest single contributor to raw speed?

glutes

calves

or does having strong hip flexors help as well? Or is this where the difference between slow and fast twitch fibers come into play over various distances?

gastrocnemius and soleus. (calf muscles)

Achilles' tendon

The Cheetah group

It's hamstrings. Watch a sprinter in slow motion. Followed by glutes. The contraction of the calves is simply a reaction...they contract eccentricly and act more like a spring. The concentric contraction of the hamstrings and glutes is what propels you forward. The glutes are more active when moving the thighs from a far foward flexed position. The hamstrings are the main players when it comes to speed

Alan

How did it take seven posts to even mention the hamstrings? I thought everybody knew that. Which muscle is by far the most commonly pulled by athletes of any sport trying to run fast?

runningart2004 wrote:

It's hamstrings. Watch a sprinter in slow motion. Followed by glutes. The contraction of the calves is simply a reaction...they contract eccentricly and act more like a spring. The concentric contraction of the hamstrings and glutes is what propels you forward. The glutes are more active when moving the thighs from a far foward flexed position. The hamstrings are the main players when it comes to speed

Alan

This. These sorts of studies HAVE been done and can be found in books about the kinesiology of running.

Mauna Kea wrote:

How did it take seven posts to even mention the hamstrings? I thought everybody knew that. Which muscle is by far the most commonly pulled by athletes of any sport trying to run fast?

An argument can be made for the hamstring being pulled BY the quadriceps.

Considering how fast Pistorius can run a 400, it isn't any of the muscles below the knee.

Guppy wrote:

runningart2004 wrote:

It's hamstrings. Watch a sprinter in slow motion. Followed by glutes. The contraction of the calves is simply a reaction...they contract eccentricly and act more like a spring. The concentric contraction of the hamstrings and glutes is what propels you forward. The glutes are more active when moving the thighs from a far foward flexed position. The hamstrings are the main players when it comes to speed

Alan

This. These sorts of studies HAVE been done and can be found in books about the kinesiology of running.

Yep. Any exercise physiology/kinesiology undergrad can tell you. Its the hamstrings

Alan

runningart2004 wrote:

It's hamstrings. Watch a sprinter in slow motion. Followed by glutes. The contraction of the calves is simply a reaction...they contract eccentricly and act more like a spring. The concentric contraction of the hamstrings and glutes is what propels you forward. The glutes are more active when moving the thighs from a far foward flexed position. The hamstrings are the main players when it comes to speed

Alan

would this be the same across all distances or just sprinters? And by raw speed, were talking about just basic speed from easy pace runs through race pace runs, not just top end speed?

process of elimination wrote:

Considering how fast Pistorius can run a 400, it isn't any of the muscles below the knee.

good point

All running. Not just sprinting. Glutes are even less active at slower speeds due to lower range of motion in the hips vs faster running. So any running depends heavily on the hamstrings.

Alan

There was a very good collegiate 400m hurdler from 30 years ago who was said to be actually missing his hamstring in one leg.

Explain that.

Straw M Thoroughman wrote:

There was a very good collegiate 400m hurdler from 30 years ago who was said to be actually missing his hamstring in one leg.

Explain that.

Missing hamstring made it easier for him to use that leg as his lead leg.

Straw M Thoroughman wrote:

There was a very good collegiate 400m hurdler from 30 years ago who was said to be actually missing his hamstring in one leg.

Explain that.

I'd explain it as a rumor.

Look at sprinters vs. distance runners. What muscle groups are more developed? Hammies and glutes. Never seen a decent sprinter without a big motor in the trunk.